This application claims priority to German Patent Application No. 100 21 481.9 filed May 3, 2000.
The present invention relates to an improved plate heat exchanger for heat exchanging media in separate loops of the heat exchanger wherein heat exchanger plates are stacked one upon the other and are metallically connected. The stacked plates each have openings disposed in a vertical manner to form flow channels for other medium/media. These flow channels are separate from each other and each is in fluid communication with channels between individual heat exchanger plates to thereby define separate loops each of which consists of flow channels interconnected by channels between the heat exchanger plates. At lease some of the channels between the plates are equipped with an internal insert.
Plate type heat exchanger technology is a well developed field where the basic structure of stacked heat exchange plates with multiple vertical medium/media flow channels into and out of the heat exchanger are common. It appears that many improvements in this technology involve the manner in which the heat exchanger plates are constructed to provide horizontal channels between the plates that interconnect the various vertical flow channels. An example of this is found in some plate heat exchangers where knobs or similar protrusions are embossed in the heat exchanger plates that form the horizontal channels for heating or cooling medium. These knobs of adjacent heat exchanger plates are in contact and soldered to each other in order to increase the strength of the plate heat exchanger. Such knobs have proven themselves in general and are therefore employed frequently because they cause almost no detectable pressure loss. However, it appears that the useful life of heat exchangers embodying such knobs where extreme loads, both from temperature shock and extreme vibrations related to operation, is not always adequate. In other heat exchangers of the plate type in order to increase the strength and useful life relative to load, temperature shock and vibration, the heat exchanger is provided with thicker outer support plates which serve as an upper and lower cover plate between which there is situated corrugated heat exchanger plates. An increased useful life for the heat exchanger is derived from this structure, but only between the aforementioned plates and the corrugated heat exchanger plates. A similar problem is found in another such heat exchanger in which a reinforcement plate is provided with an edge inserted between a base plate and a lower most heat exchanger plate. In this heat exchanger environment, loads which also act in the interior of the plate heat exchanger cannot be countered by simply employing heat exchanger plates with knobs or using a reinforcement plate.
It is against this background that the instant invention effectively overcomes the problems just described, in a manner that is readily fabricated and significantly improves the state of the art.
The plate heat exchanger embodying the invention provides a greatly increased structural strength in the interior of the heat exchanger but above all the internal structure produces turbulence in the medium brought about by securing inserts in channels between the exchanger plates which are soldered to the heat exchanger plates. The turbulence enhancing inserts of the invention, which also minimize pressure loss of medium flowing through the channels, take a structural form of an additional plate that cooperates with adjacent heat exchanger plates to create guide channels with at least one inlet and one outlet which lead from a flow channel of one medium to another flow channel of the same medium, in which sections of the additional plate that are free of guide channels are metallically connected to an adjacent heat exchanger plate and the guide channels are metallically connected to the other adjacent heat exchanger plate of the same channel.
A primary object of the invention consists of improving the useful life of the interiors of plate heat exchangers without significantly increasing pressure loss of medium flowing through channels between heat exchanger plates. This is accomplished by an additional plate that has guide channels with at least one inlet and one outlet, which lead from one flow channel of one medium to the other flow channel of the same medium.
Another object of the invention is to provide increased turbulence in the medium as the medium flows through a channel between adjacent heat exchanger plates, by the provision of a guide channel between the plates wherein the addition plate that includes the guide channel includes sections of the additional plate and guide channels that are metallically connected to an adjacent heat exchanger plate and the guide channels are additional metallically connected to the other adjacent heat exchanger plate of the same channel.
Yet another object of the invention is to provide a plate heat exchanger that produces very limited pressure loss by means of the inclusion of guide channels that have at least one inlet and one outlet wherein there is an alignment of a number of guide channels from one flow channel to the other.
Still yet another object of the invention is to provide a plate heat exchanger that has a significantly improved useful life relative to temperature shock and extreme alternating temperature loads, as well as mechanical stress because the additional plate is connected on both sides to adjacent heat exchanger plates wherein connection surfaces are very large.
A still further object of the invention is to provide a plate type heat exchanger that is nearly cubic in shape which has pairs of flow channels for different mediums in opposing covers wherein guide channels between flow channels in heat exchanger plates can run arc like and into and around flow channels in corners of the heat exchanger.
Another object of the invention is to create a highly efficient plate heat exchanger wherein additional plates that include guide channels are located in all of its channels.
A major object of the invention which dramatically diminishes pressure loss resides in the provision of two irregular shaped openings in the additional plate which are adapted to the arrangement of guide channels that interconnect flow channels wherein the openings are larger than corresponding flow channel openings in the heat exchanger plates.
Another object of the invention is to provide the irregular openings in additional plates wherein the irregular openings include indentations in a direction toward inlet or outlets of selected guide channels thereby greatly increasing heat exchanger efficiency.